1,721,023 research outputs found
Role of gonadal hormones in formalin-induced pain responses of male rats: Modulation by estradiol and naloxone administration
No full textThe aim of this study was to assess the possible mediation of endogenous opioids in the effects of gonadal hormones on the responses to formalin pain. We studied the effects of intracerebroventricular injection of estradiol and/or naloxone on the magnitude and time-course of the formalin-evoked behavioural and hormonal responses of intact and gonadectomized male rats. Animals were gonadectomized or left intact; on days 20 and 21 after surgery, they were intracerebroventricularly injected with 17 beta-estradiol (1 mu g/5 mu l) or saline. On day 22, the animals received naloxone (2.5 mu g/5 mu l) or saline intracerebroventricularly and then, 15 min later, were subcutaneously injected with formalin (50 mu l, 5%) or only pricked with a syringe needle in the dorsal hindpaw. The rats were then introduced to a testing apparatus where the formalin-induced licking, flexing and jerking of the injected limb and the other spontaneous behaviours were recorded for 60 min. At the end of the test, the animals were killed and blood was collected from the trunk. Gonadectomy and naloxone increased flexing duration independently of the other treatments. In gonadectomized rats, estrogen increased licking duration and decreased paw-jerk frequency during the first phase (0-15 min) of the formalin test. During the second phase (16-60 min), licking was increased by estrogen only in intact animals. Treatment with naloxone completely abolished all these modifications. The three measures of activity (rearing, inner and outer crossing) showed that while in sham-treated animals the gonadectomy-induced decrease in activity was completely counteracted by estrogen administration, in formalin-treated animals the gonadectomy-induced decrease was not affected by estrogen. In fact, estrogen appeared to further depress the motor activities in the formalin groups. Naloxone reversed these modifications only for outer crossing frequency, blocking the gonadectomy-induced decrease in sham-treated animals. Corticosterone plasma levels were increased by formalin only in estrogen-treated animals, independently of naloxone.
In conclusion, these data indicate an important role of both male gonadal hormones and estrogen in formalin-pain responses, acting through opiate and non-opiate mechanisms
Androgens modulate the behavioural and neuronal effects of repeted nociceptive stimulation in male rats
No full textSex differences in the olfactory stimulation-induced effects on the formalin test
No full textAromatic plants and their oils have long been known to exert various psychological and physiological effects on the human mind and body. The ability of olfactory input to stimulate, suppress or modulate various types of behavior in mammalian species has repeatedly been demonstrated. However, no data are available concerning tonic long-lasting pain. The formalin test is a well-characterized method to induce tonic long-lasting pain that shows several features of clinical pain. In the present experiment, male and female rats were subcutaneously injected with 50 μ1 of dilute formalin (5%) and introduced to a hole-board apparatus. Under the bottom of the hole-board, half of the animals received lemon essence in water and half only water. During the test, the formalin-induced responses (licking duration, flexing duration and jerking frequency of the injected limb) and other spontaneous behaviors (rearing, grooming) were recorded. Sixty minutes later, the animals were killed and blood was collected from the abdominal aorta to determine corticosterone plasma levels. The results showed a clear reduction of licking in the lemon essence group during the first 25 min of the test; the effect was greater in female than male rats. There were no differences between the groups in flexing and jerking during the first phase (0-15 min); however, the levels were lower in the lemon-treated group throughout the second phase (16-60 min), the greatest reduction occurring at 16-30 min of the formalin test. Rearing and grooming were increased by the lemon odor only in sham-treated animals, while in formalin-treated ones there were no differences. The present results clearly indicate the ability of lemon odor to modulate persistent pain in male and female rats and support further studies to better define the neuronal circuits involved
Gonadal hormones and pain modulation
No full textIn a number of animal and human studies, males and females have been shown to differ in their responsiveness to noxious stimuli [1-5]. In humans, many chronic painful syndromes are more common in women than in men. For instance, certain chronic inflammatory conditions, such as rheumatoid arthritis, complex regional pain syndrome and fibromyalgia, have a lower incidence in men than in women [6-9]. Additionally, male rodents typically have higher pain thresholds than females, and gonadectomy lowers the pain threshold in males. There is also a sex difference in the efficacy of the opioids widely used in experimental and clinical studies to test analgesia. For example, male rodents (but not humans) are more sensitive than females to the antinociceptive actions of morphine [10-13]. © Springer 2008
Effects of formalin pain on hippocampal c-Fos expression in male and female rats
No full textImmediate early genes are crucial intermediates in a cascade linking membrane stimulation to long-term alterations of neuronal activity. In the present experiment, we performed immunohistochemistry for c-Fos to determine the effects of persistent pain on cells of the hippocampus of male and female rats. Animals were subcutaneously injected with formalin (50 mu l, 10%) and perfused: 2 h later, time 2; 24 h later, time 24; 24 h later after 20 min of the open-field test, time 24/OF. Controls were left undisturbed. In control, c-Fos was higher in females than in males in all hippocampal fields. In males at time 2, formalin increased c-Fos in the dentate gyrus (DG) and CA3 fields; at time 24, c-Fos returned to the control level; at time 24/OF, c-Fos was higher than in control in the DG, but not in the other fields. In the formalin-treated females at time 2 and at time 24, c-Fos levels were lower, or tended to be lower, than in control in all hippocampal fields; at time 24/OF, c-Fos levels in the DG were higher than in control and in males. In conclusion, persistent pain had different effects on c-Fos in the hippocampal subfields, depending on the time after treatment and the sex of the subject
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Naloxone but not estradiol, affects the gonadectomy-induced increase in hippocampal cholineacetyltransferase activity in male rats.
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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